Cutting assembly for circular knitting machines



April 2, 1963 J. DE Moss ETAL CUTTING ASSEMBLY FOR CIRCULAR KNITTINGMACHINES Filed July 20, 1961 FIGI.

FIJG. 2.

INVENTORSI J OHN DeMOSS ROBERT PE E L ATTYS.

United States Patent 3,083,553 CUTTING ASSEIVIBLY FOR CERCULAR KNITTINGMACHKNES John De Moss, Somerdale, N1, and Robert Peel, Phiiadeiphia,Pa., assignors to Singer-Fidelity, Inc, Philadelphia, Pa, a corporationof Delaware Filed July 20, 1961, Ser. No. 125,585 3 Claims. (Ci. 6614t3)This invention relates to cutting devices used on circular knittingmachines, particularly ladies fine gauge seamless hose machines, wherethe ends caused by the yarn changes are cut short as knitting proceeds.

One type of such device is shown in U.S, Patent 2,824,- 383. Thesedevices consist of a serrated ring Where the teeth are in closeproximity to the back of the needles and rotate in synchronizationtherewith. The teeth are on the edge of what can be called asubstantially flat ring. The flat surface of this ring engages a bladeor similar cutter having a cutting edge. In some cases the cutting edgeis raised out of action when not needed and in other cases is left inpermanent contact with the rotating flat surface. The teeth of the flatserrated ring cooperate with the cutter or knife edge so that when athread is entrapped in any tooth on the ring it is severed as it passesthe point of engagement with the cutter. In practice this combination ofmechanism sufiers from certain disadvantages associated with wear onboth the ring and the knife or cutter, failure to cut due to foreignsubstances raising the cutter from the surface of the ring and the like.In practice, most of the known combinations of mechanism made inaccordance with the above inventions have also required considerableskill in the initial setting to insure that they operate satisfactorily,

A primary object of the present invention is to obviate some of thesedifficulties and to completely remove the necessity for skilledadjustment in the initial setting.

Another object of the present invention is to provide an improved cutterassembly of simple manufacture which is self-aligning, self-cleaning,and self-sharpening.

More specifically, the present invention contemplates a serrated ringsubstmtially as shown in the above patents, and a cooperating cutterhaving a flat annular face with a sharp edge and placed on the fiat edgeof the serrated ring with part of its circumference slightly overlappingthe edge of the teeth with means to exert pressure forcing the annularface into fiat and intimate contact with the flat surface of theserrated ring.

All of the objects of the various features and details of theconstruction and operation thereof are more fully set forth hereinafterwith reference to the accompanying drawing wherein:

FIG. 1 is a fragmentary plan view of the dial of a circular knittingmachine embodying a cutting assembly in accordance with the presentinvention;

FiG. 2 is a side elevational view of the assembly as seen from the line22 in FIG. 1;

FIG. 3 is a sectional view taken on the line 3--3 of FIG. 2; and

FIG. 4 is a perspective view of the cutting assembly.

Referring to the drawing, the knitting machine comprises a conventionalrotary needle cylinder having a circle of needles 11 mounted therein. Adial 12 rotates with the needle cylinder and is covered by a stationarydial cap 13. A latch ring 15 surrounds the needle circle and comprises apart of the stationary frame of the machine. The latch ring mounts oneor more feed stations (not shown) which operate in the usual manner toinsert yarns into and withdraw yarns out of action,

In accordance with the invention, a cuttter mechanism is provided,preferably one for each feed station, for example as shown at 21. Thecutter assembly 21 cooperates with a serrated or toothed annular ring 23mounted on and for rotation with the dial 12. The upper face of the ring23 is provided with a flat surface 2-5 projecting from the dial, and theteeth 24 of the ring 23 meet the flat portion 25 of the ring in cuttingedges 25. The cutting assembly 21 cooperates with the cutting edges 26to sever the yarns engaged by the teeth 24.

As shown in the drawing, the preferred embodiment of the cutter assemblycomprises a cutter element 30 in the form of a short cylinder withconical indentations 31 on the two end surfaces thereof. Each of the endsurfaces is lapped or ground to form a flat annular face 32 having asharp edge 34 at the junction with the cylindrical surface 33. The lowerannular face 32 of the cylinder is engaged with the flat surface 25 ofthe ring 23 with a part of its circumference overlapping the outerperiph cry of the surface 25.

#Means is provided on the stationary dial cap 13 to accurately positionthe cylinder 30 and bias the annular face 32 thereof into fiat andintimate contact with the flat face 25 of the annular ring 23. In theillustrated embodiment of the invention, the positioning means comprisesa spring finger 40 mounted on the dial cap 13 as indicated at 41 andhaving a resilient arm 42 disposed generally circumferentially of theannular ring 23. The free end of the arm 42 is provided with a dependingtoe 43 which terminates at its lower extremity in a point 44 whichengages in the conical indentation 31 on the upper surface of the cutterelement. The point contact of the leg with the cutter element permitsthe cutter to be self-aligning, so as to insure flush engagement betweenthe annular face 32 and the upper surface 25 of the serrated ring. Thisautomatic self-alignment of the cutter with the serrated ring eliminatesthe necessity for skillful installation and adjustment of the cutter andeliminates the necessity for the extremely close tolerances which wererequired in the prior cutter elements.

Because of the overlapping of the cutter with the outer periphery of theteeth 24 and the point contact between the leg 43 and the indentation31, the frictional contact between the face 32 and the surface 25 duringnormal rotation of the serrated ring 23 causes the cutter to rotateabout the leg point 44. As the cutter rotates, the rotation causes theentire annular face 32 of the cutting element to pass over the surface25 and thereby maintains the annular face 32 and the edge 34 sharp andfree of ridges or other indentations. The rotation of the cutter alsooperates to discharge any foreign matter which may lodge between thecutter and the serrated ring In this manner, the cutter assembly is bothself-sharpening and self-cleanmg.

It is apparent that the cutter of the present invention is of extremelysimple manufacture and can be readily produced in a variety of very hardsteels or special alloys, such as tungsten carbide. Both the upper andlower surfaces 32 of the cutter may be lapped or ground to create twocutting edges 34, whereby the cutter may be reversed if one edge shouldbecome damaged or otherwise inefiective in use.

It is preferred to form the cutter element 30 as a cylinder with conicalindentations in the upper and lower surfaces, but it is entirelypossible to form the element as a cone, either truncated or pointed atthe top. In this case, the cutter is held doum by a resilient flexiblemember having an aperture adapted to receive the upper end of thecutter. In such a case, the base of the conical member would be providedwith a suitable indentation or ofiset to provide an annular face similarto the face 32. In this way, it is not necessary to provide the extremeflatness which would be otherwise required to insure proper cuttingaction.

After the cutter assembly has been assembled and put into operation, itis desirable to retain the cylindrical or other cutter in position whilethe assembly is partially dismantled, for example when lifting the dialcap from the dial. One method of accomplishing this is by using amagnetized element for the arm 40. Thus, when the serrated ring isremoved from engagement with the cutter element, the magnetized armretains the cutter element while adjustments were made in the knittingmachine.

While a particular embodiment of the present invention has been hereinillustrated and described, it is not intended to limit the invention tosuch disclosure, but changes and modifications may be made therein andthereto within the scope of the following claims.

we claim:

1. In a circular knitting machine having a rotary cylinder mounting acircle of needles, a toothed ring mounted for rotation with saidcylinder adjacent to and within said needle circle, said toothed ringhaving an upper flat surface cooperable with said teeth to form aplurality of cutting edges, and a stationary dial cap superimposed onsaid ring; a cutter for 'yarn engaged in the teeth of said ringcomprising a cutterelement having an annular face engaged flush againstthe fiat surface 'of said toothed ring, said annular face cooperatingwith said cutting edges to sever the yarn engaged in the teeth of saidtoothed ring,

4 said cutter element being mounted for self-alignment with said flatsurface and being rotatable by said ring about the axis of said annularface.

2. Apparatus according to claim 1 wherein said annular face of thecutting clement projects beyond the outer periphery of said fiat surfacewhereby the frictional engagement of said annular face on the fiatsurface of said toothed ring elfects rotation of said cutter element.

3. Apparatus according to claim 1 wherein said cutter element isgenerally cylindrical in form and is provided with a generally conicalindentation on its upper surface coaxial with said annular face, andincluding a mount ing arm secured to said dial cap and having a pointprojecting into the conical indentation on said upper surface, said armbeing resiliently fiexible'to thereby bias said cutter into flushengagement with said surface of the toothed ring, the point and saidindentation cooperating to provide for self-alignment of said cutter.

References Cited in the file of this patent UNITED STATES PATENTS2,592,019 Farnett Apr. 8, 1952 2,824,436 Stack et a1 Feb. 25, '19582,970,460 Mahler et al. Feb. 7, 1961

1. IN A CIRCULAR KNITTING MACHINE HAVING A ROTARY CYLINDER MOUNTING ACIRCLE OF NEEDLES, A TOOTHED RING MOUNTED FOR ROTATION WITH SAIDCYLINDER ADJACENT TO AND WITHIN SAID NEEDLE CIRCLE, SAID TOOTHED RINGHAVING AN UPPER FLAT SURFACE COOPERABLE WITH SAID TEETH TO FORM APLURALITY OF CUTTING EDGES, AND A STATIONARY DIAL CAP SUPERIMPOSED ONSAID RING; A CUTTER FOR YARN ENGAGED IN THE TEETH OF SAID RINGCOMPRISING A CUTTER ELEMENT HAVING AN ANNULAR FACE ENGAGED FLUSH AGAINSTTHE FLAT SURFACE OF SAID TOOTHED RING, SAID ANNULAR FACE COOPERATINGWITH SAID CUTTING EDGES TO SEVER THE YARN ENGAGED IN THE TEETH OF SAIDTOOTHED RING, SAID CUTTER ELEMENT BEING MOUNTED FOR SELF-ALIGNMENT WITHSAID FLAT SURFACE AND BEING ROTATABLE BY SAID RING ABOUT THE AXIS OFSAID ANNULAR FACE.